The present invention relates to the field of electronic modules, and, more particularly, to electronic modules including a substrate for cooling one or more electronic devices and associated methods.
Electronic devices are widely used in many types of electronic equipment. One electronic device is the integrated circuit which may include a silicon or gallium arsenide substrate and a number of active devices, such as transistors, etc. formed in an upper surface of the substrate. It is also typically required to support one or more such integrated circuits in a package that provides protection and permits external electrical connection.
As the density of active devices on typical integrated circuits has increased, dissipation of the heat generated has become increasingly more important. In particular, a relatively large amount of heat may be generated in multi-chip modules (MCMs), microwave transmitters, and photonic devices, for example.
One device which has been used in a variety of applications, including electronic circuit modules, to provide high thermal transport over long distances is the so-called xe2x80x9cheat pipe.xe2x80x9d A heat pipe is a sealed system that includes an evaporator, a condenser, an adiabatic region connecting the evaporator and condenser for liquid and vapor transport, and a capillary or wick for circulating cooling fluid therein. Heat pipes enjoy an advantage over other forms of heat regulating devices in that they can transfer heat without the need for a mechanical pump, compressor or electronic controls, which may provide space savings in certain instances.
An example of an MCM which uses a heat pipe is disclosed in U.S. Pat. No. 5,216,580 to Davidson et al. entitled xe2x80x9cOptimized Integral Heat Pipe and Electronic Module Arrangement.xe2x80x9d This MCM includes electronic circuit components mounted on one side thereof and a thermal wick mounted on another side. A heat pipe evaporator and condenser assembly is attached to the MCM and wick assembly. Furthermore, a suitable working fluid is introduced into the heat pipe assembly which is then hermetically sealed.
Of course, cooling devices generally need to be on the same size scale as the electronic devices they are intended to cool. Yet, the benefits associated with heat pipes are subject to scaling limitations. That is, ever increasing packaging densities, which put high power devices in close proximity with conventional circuitry, may require that larger amounts of heat be transferred more quickly than is possible using conventional heat pipe assemblies not having a pump.
In view of the foregoing background, it is therefore an object of the invention to provide an electronic module and related methods which provides adequate cooling of one or more electronic devices and has relatively small dimensions.
This and other objects, features, and advantages in accordance with the present invention are provided by an electronic module including a cooling substrate, an electronic device mounted thereon, and a plurality of cooling fluid dissociation electrodes carried by the cooling substrate for dissociating cooling fluid to control a pressure thereof. The cooling substrate may have an evaporator chamber adjacent the electronic device, at least one condenser chamber adjacent the heat sink, and at least one cooling fluid passageway connecting the evaporator chamber in fluid communication with the at least one condenser chamber.
More particularly, the electronic module may drive the plurality of cooling fluid dissociation electrodes, for example, by sensing a temperature thereof and driving the plurality of cooling fluid dissociation electrodes responsive to the sensed temperature. The plurality of cooling fluid dissociation electrodes may also allow cooling fluid dissociation during manufacture of the electronic module. Each of the cooling fluid dissociation electrodes may include metal, and the metal is preferably resistant to corrosion from the cooling fluid. For example, the metal may include at least one of gold and nickel.
Furthermore, the electronic module may also include a heat sink adjacent the cooling substrate. The plurality of cooling fluid electrodes may include an evaporator thermal transfer body connected in thermal communication between the evaporator chamber and the electronic device and at least one condenser thermal transfer body connected in thermal communication between the at least one condenser chamber and the heat sink. The evaporator thermal transfer body each and the at least one condenser thermal transfer body may have a higher thermal conductivity than adjacent cooling substrate portions. Further, the evaporator thermal transfer body and the at least one condenser thermal transfer body may have thermal conductivities greater than about 100 Watts per meter-degree Celsius.
Moreover, the evaporator thermal transfer body, the at least one condenser thermal transfer body, and the at least one cooling fluid passageway may cause fluid flow during operation of the electronic module without a pump. The evaporator thermal transfer body may include a wicking portion exposed within the evaporator chamber for facilitating cooling fluid flow by capillary action. Also, the at least one condenser thermal transfer body may include at least one wicking portion exposed within the at least one condenser chamber for facilitating cooling fluid flow by capillary action.
Additionally, the cooling substrate may further include projections extending inwardly into the at least one cooling fluid passageway for facilitating cooling fluid flow by capillary action. The cooling substrate may also include projections extending inwardly into the evaporator chamber and the at least one condenser chamber for facilitating cooling fluid flow by capillary action.
A method aspect of the invention is for controlling cooling fluid pressure in an electronic module including a cooling substrate and an electronic device carried by the cooling substrate. The cooling substrate includes an evaporator chamber, at least one condenser chamber, and at least one cooling fluid passageway connecting the evaporator chamber in fluid communication with the at least one condenser chamber. Further, the electronic device is carried by the cooling substrate adjacent the at least one condenser chamber. The method includes driving a plurality of cooling fluid dissociation electrodes carried by the cooling substrate for dissociating cooling fluid to control a pressure thereof.